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Alpha RoS Light Limited Edition Jacket

In an industry full of acronyms, Castelli adds to it with its Alpha RoS Light Limited Edition Jacket where the RoS stands for Rain or Shine, meaning this jacket offers both wind and water protection in formidable weather and also breathes well enough and manages moisture when conditions are more favorable too. Castelli does a wonderful job of calling out the temperature ranges for its kit and this jacket is well suited to its suggested temperature range of 46 - 59 degrees Fahrenheit. Depending on base layers and personal comfort zone this can of course vary but it's nice to know that this jacket can handle a bulk of our shoulder season rides, rain or shine.

The versatility of this jacket is what really makes it extraordinary. By using highly advanced fabrics, along with reduced seams and sealing them when necessary, this jacket is ideal in cooler dry temps while holding its own on milder, wetter conditions. Castelli calls it functional waterproofing meaning it won't be absolutely dry like an out-an-out rain jacket, however, it will keep you warmer and drier over a wider range of conditions.

Gore's Windstopper 150 membrane is the key to the jacket's versatility, but Castelli's cycling clothing know-how is why it's ideally suited for serious cold-weather training and racing. Part of that is the inclusion of a rear panel of Castelli's Nano Flex Xtra Dry, a thermal material with a DWR treatment that dumps excess heat, improves breathability, and maintains a water-resistant surface across the entire jacket.

The Windstopper layer is separated from a thermal layer across the front panel, so you can unzip the protective shell but leave the thermal layer intact, letting you moderate the exposure on long climbs without baring your chest to frigid, wintery blasts. Skiers and alpinists use Windstopper indiscriminately: their goal is to stay warm and dry at all costs. Cyclists' needs, on the other hand, change over the course of a ride depending on intensity, climbing, descending, etc., so we need the protection to change with us in real time. The Alpha solves that problem.

Castelli's versatile jacket for training and racing

Windstopper 150 membrane blocks wind and water and remains breathable

Rear thermal panel vents and keeps the rain at bay

Separate thermal mid-layer provides targeted warmth

Slim fit eliminates flapping material during tempo base miles

Maintains breathability to manage moisture during hard efforts

Raw edge hem and cuffs reduce bulk and maintain coverage

Masters of cycling apparel, Castelli knows the needs of cyclists in variable conditions

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Weatherproof

The Castelli Alpha RoS Light jacket makes riding on any day a possibility. The jacket layers well over a baselayer or a jersey and gives you even more pockets-for-snacks.

I've worn the jacket in temps down to about 35, paired with a windstopper jersey, and been quite comfortable. The cuff fits well underneath gloves, helping to avoid the all-too-common discomfort of cuff/sleeve/glove. I was initially skeptical of the liner vest situation, but let me tell you: gamechanger! It makes this jacket even more versatile for temperature ranges of 32-55 degrees Fahrenheit or so.

I'm 5'6" 145lbs, and the large fit well with plenty of room to layer beneath it. A medium also fit, but less ideal for wearing a jersey underneath.